我正在尝试使用 CSS 设置页面样式。我用 div 构建我的页面，并通过外部 css 文档设置它们的样式。这是我到目前为止所拥有的：
显然这不是我想要的！出于某种原因，菜单（通过 ul 构建）不会留在菜单 div 中。另外，我的页脚也遇到了同样的问题。我究竟做错了什么？
这是我的aspx页面+ css文档：ASPX：
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="home.aspx.cs" Inherits="AppointmentsDrivingLicense_C_and_D.home" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>A.C.T. | Appointments 1.0.0</title>
<link rel="stylesheet" type="text/css" href="styles/main.css" />
</head>
<body>
<div id="content">
<!-- BEGIN HEADER -->
<div>
<div id="logo">
<div id="programName">
<p><b>ACT</b>Appointments 1.0.0</p>
</div>
<div id="logged">
<p>User | <a href="#">Afmelden</a></p>
</div>
</div>
<div id="menu">
<ul>
<li><a href="#">Home</a></li>
<li><a href="#">About</a></li>
<li><a href="#">Contact</a></li>
</ul>
</div>
</div>
<!-- END HEADER -->
<!-- BEGIN BODY -->
<div id="body">
<b>Home</b>
<hr />
<p>
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer tincidunt, elit eu sollicitudin consectetur, nulla velit congue massa,
sit amet hendrerit elit massa vel nisl. Sed consequat aliquam risus ac imperdiet. Etiam placerat metus vitae augue accumsan a pretium lacus varius.
In facilisis risus vitae enim varius at lobortis eros fermentum. Nunc sit amet enim id ligula scelerisque tincidunt vitae sit amet nisl.
Fusce tellus augue, interdum non semper vitae, semper sed lectus. Nam ultricies massa non erat suscipit a vulputate est bibendum.
Nullam cursus ante et ipsum accumsan lacinia. Mauris eget diam sed enim dapibus rutrum ut vel mauris. In faucibus convallis ultrices.
Donec pharetra tellus at sem euismod eget consectetur arcu luctus.
</p>
<p>
Morbi scelerisque cursus mi ac suscipit. Curabitur quis nisi ante. In arcu diam, mattis a tristique sit amet, adipiscing sed nulla.
Nunc felis massa, ullamcorper eget tristique quis, vestibulum eu tellus. In hac habitasse platea dictumst. Pellentesque nec lacus nibh,
a egestas neque. Sed sed mi viverra orci luctus fringilla. Praesent dictum elementum felis, vitae gravida dolor vehicula at.
Vestibulum nec molestie tortor. Quisque vel arcu dolor. Nulla facilisi.
</p>
</div>
<!-- END BODY -->
<!-- BEGIN FOOTER -->
<div id="footer">
<div id="footer-left">
<p>Welkom user</p>
</div>
<div id="footer-right">
<p>ACT-KM © 2013</p>
</div>
</div>
<!-- END FOOTER -->
</div>
</body>
</html>
CSS 文档：
*{
margin: 0px;
padding: 0px;
}
body {
background-color: lightgray;
}
#content{
margin-left: 45px;
margin-right: 45px;
border-left: solid 1px black;
border-right: solid 1px black;
}
#footer{
background-color: #E8E8D9;
font-size: 12px;
padding-bottom: 5px;
padding-top: 5px;
border: solid 1px black;
/*border-top: solid 1px black;*/
}
#footer-left{
float: left;
padding-left: 10px;
}
#footer-right{
float: right;
padding-right: 10px;
}
#body{
padding-left: 20px;
padding-right: 20px;
padding-bottom: 10px;
padding-top: 10px;
background-color: white;
}
#logo{
/*background-color: #E8E8D9;*/
background-color: red;
}
#programName p{
float: left;
padding-left: 20px;
padding-bottom: 10px;
padding-top: 10px;
font-size: 20px;
}
#logged{
float: right;
font-size: 12px;
padding-right: 10px;
padding-bottom: 10px;
padding-top: 10px;
}
#menu{
clear:both;
border-top: solid 1px black;
border-bottom: solid 1px black;
padding-left: 10px;
padding-top: 3px;
padding-bottom: 3px;
}
#menu ul{
list-style-type: none;
}
#menu li{
float: left;
}
#menu li a{
display: block;
padding-left: 15px;
padding-right: 15px;
text-decoration: none;
font-family: Georgia, 'Times New Roman', serif;
font-size: 16px;
}
提前致谢！凯文